My friend has a 2009 CFMoto 250T-F. The manual specifies DPR7EA-9 spark plugs. He lives in a cooler climate and is trying one heat range hotter plug, DRP6EA-9. He was curious about any long term durability issues. He always uses premium fuel.

It's a 244cc single-cylinder, 4-stroke, watercooled, carbureted engine with CDI ignition. Compression ratio is 10:1.

Does anyone have any comments or suggestions on what spark plug heat ranges they have tried or what works best on this engine?